A primary key is a column or set of columns that uniquely identifies each row in a relational table. In PostgreSQL, defining an id column as a primary key establishes the table’s row identity. section 5.1
Assigning generated identifiers
Define an integer id as the primary key, create a sequence starting at 1, and set the column default to nextval from that sequence. This lets inserted rows receive sequential identifiers while preserving uniqueness.
